This invention is concerned with combine harvesters having axial flow rotary separators and more particularly with those in which the separator is transversely mounted and forms part of the header of the combine.
It has long been known that axial flow rotary separators are, at least potentially, more efficient than straw walker-type separators in terms of separation capacity per unit volume (volumetric efficiency), but only comparatively recently have such separators been used commercially in significant numbers. The market place was demanding ever larger combine capacity but further increases in conventional combine size (especially vehicle width and even length) were becoming unacceptable because of transport and handling considerations. The axial flow rotary separator thus became more acceptable in spite of certain disadvantages such as higher specific power consumption and some material handling limitations. However, even though machines using axial flow rotary separation have entered the large combine market with some success, their configuration has been characterized by a direct substitution of the rotary separator for the traditional straw walkers. Certainly, in these machines, axial flow rotary separation has generally been combined coaxially with axial flow rotary threshing, but in most cases the rotor axis is disposed fore-and-aft and the rotary threshing and separating apparatus occupies essentially the space previously occupied by the conventional threshing cylinder and straw walkers. This in-line arrangement falls short of realizing the full volumetric efficiency or space saving potential of axial flow rotary separation, the "functional package" of which is essentially cylindrical. In current commercial machines, the separators are generally enclosed within more or less rectangular box-like combine bodies, and the disparity of shape between separator and body, dictated by factors other than the separator shape, results in "wasted" space around the separator and makes it relatively less accessible for service and repair. In another type of commerical machine an axial flow rotary separator is mounted transversely in the combine body but this arrangement also suffere from some of the same space utilization disadvantages as the in-line configuration.
In the past, attempts have been made to include the crop threshing and separation functions within the header of the combine. Conventionally, the header of a combine includes only means for gathering and converging the crop and delivering it to the body of the combine for processing (threshing, separating and cleaning). The header/separator configurations known to have been tried have generally been awkward and cumbersome. They may be characterized at least in part, as simply putting together new combinations or configurations of old components (conveying and functional elements such as feeding conveyors and conventional threshing cylinders and even straw walkers) arranged in a header environment. When header-mounted transversely oriented axial flow separation has been attempted, it has been found necessary to use at least two separate elements to achieve the threshing and separation. For example, threshing and separating elements are placed in tandem. And commonly, a beater feeder must be used between the gathering or platform portion of the header and the threshing and separating portion.
Even a conventional header for a large capacity combine raises problems of efficient structural design and vehicle stability and "exotic" solutions have already been proposed, such as the use of new lighter weight materials, or even conceding that the maximum practical width of gatherer may have been reached. Thus, attempting to include in the header the additional functions of threshing and separation, obviously only severely intensifies the structural and stability problems. So far as is known, no header-mounted separator has been sufficiently space and functionally efficient to achieve commercial success.